This is slightly different from a similar projection by Stephen Fisher of Trinity College, Oxford, last week, who forecast that Labour and the Conservatives would have almost exactly the same number of seats in a hung parliament. Both projections try to extrapolate from current opinion polls, based on the average movement of party support in the year before an election. According to Polling Observatory, there has been, on average, a swing of 2.7 percentage points to the government party in the 12 months before elections.

What is interesting is that Labour's forecast is creeping up because the opposition party in the past has tended to lose ground around this time, and Ed Miliband's party is currently holding steady.